Little is known about the clinical aspects of depression care received by females, relative to males, in primary care settings. In particular, few studies have addressed whether depressed men and women respond similarly to treatment for depression within usual care primary care settings. Recently, a number of studies have examined the efficacy and cost- effectiveness of models designed to improve depression treatment for primary care patients by increasing the number of patients who receive guideline-concordant care. Yet, we do not know whether these quality improvement (QI) efforts have been equally effective for men and women. It is important for policy makers to know whether existing QI programs successfully reduce gender disparities or inadvertently create new disparities. The proposed study will contribute to research knowledge of these issues using a unique, common data base from four quality improvement studies for depression, called QID. This data base includes 1498 primary care patients with major depression plus an additional 500 depressed patients who did not meet QID exclusion criteria from Partners in Care (PIC), an AHRQ-funded PORT II for depression. The proposed study will 1) determine if there are differences in quality of care received, compliance and health outcomes for depressed men and women in usual care; 2) determine whether QI programs for depression reduce existing disparities in quality of care and outcomes for men and women; 3) determine (for PIC only) whether costs and cost-effectiveness of QI programs differ for men and women; and 4) determine whether the effect of appropriate treatment on outcomes differ for men and women. Multiple factors that explain possible gender differences will be explored. Estimates of treatment effectiveness under QID's more naturalistic conditions are the type of data needed to inform policy debates over mental health care coverage. Results from the proposed study will enable policy makers to refine treatment and services interventions to ensure gender-equitable care for this prevalent and disabling condition.